1. Field of the Invention
This invention relates to apparatus for growing plants singly in individual spaced-apart root support beds and to a method for cultivating the plants in said apparatus and for varying the spacing of the plants according to their growth stage. In particular, the invention relates to a system of elongated channels having interior ducts for continuously supplying fluid growth regulating media to plants spaced apart on elongated members above the bottoms of the channels, the spacing between corresponding plants in adjacent channels being increased as the plants mature.
2. Description of the Prior Art
The art known as hydroponics of growing plants in nutrient solutions, with or without a porous inert medium to provide mechanical support, has been practiced with oblong boxes filled to a predetermined level with an aqueous nutrient solution. The plants are typically supported on a holding stand such as a perforated cover on each box that allows the roots of the plants to depend into the nutrient solution, as shown in U.S. Pat. No. 2,189,510 issued Feb. 6, 1940 to M. W. Swaney.
In the Swaney patent, individual plants are held in support blocks set in spaced holes in the cover. The plants can be rearranged by shifting them to different holes in the cover. Because the plant roots continually excrete toxic matter, the nutrient solution in the boxes must be drained and replaced by fresh solution periodically.
Another procedure for increasing the spacing of plants grown hydroponically is shown in U.S. Pat. No. 3,927,491 issued to R. S. Farnsworth. The plants are placed initially on small buoyant rafts spaced close together and floating in a nutrient solution. As the plants grow larger and heavier, the small rafts are placed on larger rafts, which provide greater buoyancy and increased lateral spacing.
In conventional soil cultivation of plants grown singly in individual pots, it is a known procedure to transplant to larger pots and to increase the spacing between pots, as described in "Crysanthemums The Year Round" by Searle and Machin, published by Blandford Press, London in 1968.
Still another system for increasing the space between plants as they grow is disclosed in U.S. Pat. No. 3,254,447 issued to O. Ruthner on June 7, 1966. The Ruthner system comprises a ladder-like conveyor belt having elongated vertically oriented loops. Plant containers are suspended from spaced transverse bars or "rungs" of the conveyor belt. The belt moves continuously, and the containers dip into open receptacles of nutrient solution periodically each time they traverse a lower reversing point between two vertical paths of the belt. In embodiments shown in FIGS. 9 and 10 of the patent, the belt follows a serpentine path, and the spacing between adjacent vertical loops increases to accommodate progressively larger plants as they mature.
Thus, it is well known in the prior art of hydroponics cultivation that the nutrient solution supplied to the plants must be replenished or replaced periodically to avoid excessive buildup of toxins excreted by the plants. It is also known to minimize the area required for growing plants by cultivating the plants singly in individual beds or pots and by shifting the beds or pots to provide more space as the plants grow larger.